This invention relates to structural columns and more particularly to light weight, inflatable pneumatic structural columns which are erectable by internal pressurization.
Previously, inflatable structural members, constructed of a permanently flexible casing utilizing elastomeric materials such as synthetic rubber, have been proposed. These members are storable in a collapsed condition and are subsequently stiffened by inflation. However, such members lose their shape and stiffness and may even collapse upon leakage or exhaust of the inflating medium. In addition, due to the nature of the flexible material used, the inflated members, while relatively stiff, suffer from reduced strength and resistance to torsional and/or bending forces. Attempts to increase the torsional and bending strengths, by increasing the thickness of the casing material of such inflatable members, are met with detrimental increases in weight.
Another type of structural member constructed of resin impregnated unidirectional filaments has been proposed to alleviate the problems of reduced strength and resistance to torsional and/or bending forces. Such members, however, engendered yet another problem in that, since they were preformed, they occupied a relatively large volume of storage space. Attempts at solving this further problem included the fabrication of tapered half-columns which could be stored in nested form. Although this eased the storage problem somewhat, such construction complicated the structural erection since twice as many inter columnar connections are required.
Consequently, it is desirable to provide a light weight, structural column having superior strength characteristics which is storeable in compact form.